MDA Technologies 2/2016

Linear axis technology

Linear axis technology for simulating the emergencies in the high seas Klaus-J. Hermes Knowing the weather conditions in the high seas is very important, especially in the case of rescue operations for the evacuation of a drilling platform. For this purposes the Marin research institute in co-operation with energy company Statoil has developed a simulation software tool. This tool helps in predicting the trajectory and impact in water of the free fall rescue boats that are generally used for these kinds of missions. A linear axis from Rollon was used in true-to-scale model to simulate the situation. Author: Klaus-J. Hermes, Marketing Director Rollon, Düsseldorf DRIVE TECHNOLOGIES On drilling platforms the safety of employees is the top priority. Under certain hazardous circumstances, it is impossible to evacuate a drilling platform via helicopter or a ship. For these rare emergencies, special free fall rescue boats were developed back in 1960s. The international energy company Statoil, in cooperation with the Maritime Research Institute Netherlands (Marin), took on the task of determining the weather conditions under which such a free fall rescue boat can be used safely. For the past four years researchers at Marin have therefore been developing a computer simulation that can predict how such a rescue boat will drop and move in the water. True-to-scale models made it possible for the researchers at the institute to test the simulation software ‘Dropsim’. Testing with true-to-scale models To collect the data for validation of the Dropsim software, Marin developed free fall rescue boats that are equipped with n optical measuring system, n pressure sensors n acceleration sensors n wireless operations n automatic controls To practice for emergency, different environmental conditions such as weather, currents, wind and waves were simulated in the institute’s basin while the test objects were put into the water. The models were dropped into the simulated sea at different angles and speeds. As part of the development and validation of ‘Dropsim’, tests were also conducted with a ‘generic’ type of rescue boat. “The model of the generic free fall rescue boat looks like a kind of sphere,” explains Tiemen de Haij, an engineer at Marin. The biggest challenge was that all of the movements had to be controlled and repeated frequently. For transferring the conditions from the tests to the simulation model and for comparison purposes, the sphere had to be guided as it dropped into the water. MDATechnologies 2/2016

01 For Marin institute it was important that the rail and the carriage are sufficiently strong and fast 02 When the rescue boat impacts the water, all forces and moments are measured in six directions 03The R-Smart 220 SP linear axis from Rollon is the largest axis in this series “For this purpose we built a frame on which a large linear axis was mounted,” explains de Haij. The researchers used the ‘R-Smart 220 SP’ axis from Rollon. It has a cross section of 220 mm and the carriage can execute a stroke of 6 m. Linear axis for heavy loads The ‘R-Smart 220 SP’ linear axis from Rollon is the largest axis of the Smart series. It is equipped with a self-supporting frame of anodised aluminium. The unit is driven by a synchronous belt made of polyurethane with steel reinforcement and the ‘AT’ tooth profile. The Smart series is well suited for heavy loads, demanding work cycles, assembly of self-supporting beams or frames and for use in industrial environments. The maximum static payload of the linear axes is 8,880 N (Fx), 237,000 N (Fy) and 237,000 N (Fz). The technology of the linear ball bearing guides combines high load capacities with smooth movement up to a speed of 4 m/s and an acceleration of 50 m/s 2 . The maximum usable stroke length of the single linear unit is 5,730 mm. The technical properties and parameters attest to the high efficiency of the linear axis. n It can withstand high loads at long strokes n Achieves high speeds and accelerations n Guarantees smooth and quiet movement About Rollon Rollon is a global company specializing in the design and manufacturing of linear rails, telescopic rails and linear actuators that are used in wide range of industries such as aerospace, railway, medical, special vehicles, automation and industrial machinery. The company has its head office in Vimercate, Italy and has branch offices in Germany, France, Netherlands, USA, China and India. The company employs more than 300 people worldwide. The biggest challenge was that all of the movements had to be controlled and repeated frequently Rollon has expanded the series at the top end to include the R-Smart 220 SP. As with the long established sizes 120 and 160, it can be equipped with two sliders of different lengths. The diverse Smart series gives design engineers and users a broad selection of components with respect to mass, speed and acceleration for individual applications. This linear axes series can also be used for establishing multi-axis systems in packaging and pick & place applications. Successful validation due to extensive tests “For us it is important that the rail and carriage are sufficiently strong and fast,” explains de Haij. In addition, the rail had to be compatible with the Marin drive system. “Rollon was the only supplier who could fulfil these requirements. And the support offered by the company also played an important role in our decision.” The generic rescue boat was used for both free fall tests and guided tests. In the guided tests the rescue boat was fastened to the Rollon rail and equipped with force sensors. This allowed measurement of all forces and moments in 6 directions when the rescue boat reached the water. The data generated by Marin institute during these tests is very useful for the simulation model ‘Dropsim’. With this data ‘Dropsim’ can predict what can happen to the free fall rescue boat as soon as it reaches the water under extreme environmental conditions. It also becomes clear how the boat will move in the water afterwards. As a result of the extensive tests, validation of ‘Dropsim’ was completed in September 2014. Photographs: Rollon www.rollon.com MDATechnologies 2/2016